Delete CC.

cc/scheduler/delay_based_time_source.cc

Index: cc/scheduler/delay_based_time_source.cc
diff --git a/cc/scheduler/delay_based_time_source.cc b/cc/scheduler/delay_based_time_source.cc
deleted file mode 100644
index ef43524a878288d72e4b89a5fdf6ce485fc18e33..0000000000000000000000000000000000000000
--- a/cc/scheduler/delay_based_time_source.cc
+++ /dev/null
@@ -1,301 +0,0 @@
-// Copyright 2011 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "cc/scheduler/delay_based_time_source.h"
-
-#include <algorithm>
-#include <cmath>
-#include <string>
-
-#include "base/bind.h"
-#include "base/location.h"
-#include "base/logging.h"
-#include "base/single_thread_task_runner.h"
-#include "base/trace_event/trace_event.h"
-#include "base/trace_event/trace_event_argument.h"
-
-namespace cc {
-
-namespace {
-
-// kDoubleTickDivisor prevents ticks from running within the specified
-// fraction of an interval.  This helps account for jitter in the timebase as
-// well as quick timer reactivation.
-static const int kDoubleTickDivisor = 2;
-
-// kIntervalChangeThreshold is the fraction of the interval that will trigger an
-// immediate interval change.  kPhaseChangeThreshold is the fraction of the
-// interval that will trigger an immediate phase change.  If the changes are
-// within the thresholds, the change will take place on the next tick.  If
-// either change is outside the thresholds, the next tick will be canceled and
-// reissued immediately.
-static const double kIntervalChangeThreshold = 0.25;
-static const double kPhaseChangeThreshold = 0.25;
-
-}  // namespace
-
-// The following methods correspond to the DelayBasedTimeSource that uses
-// the base::TimeTicks::Now as the timebase.
-scoped_refptr<DelayBasedTimeSourceHighRes> DelayBasedTimeSourceHighRes::Create(
-    base::TimeDelta interval,
-    base::SingleThreadTaskRunner* task_runner) {
-  return make_scoped_refptr(
-      new DelayBasedTimeSourceHighRes(interval, task_runner));
-}
-
-DelayBasedTimeSourceHighRes::DelayBasedTimeSourceHighRes(
-    base::TimeDelta interval,
-    base::SingleThreadTaskRunner* task_runner)
-    : DelayBasedTimeSource(interval, task_runner) {
-}
-
-DelayBasedTimeSourceHighRes::~DelayBasedTimeSourceHighRes() {}
-
-base::TimeTicks DelayBasedTimeSourceHighRes::Now() const {
-  return base::TimeTicks::Now();
-}
-
-// The following methods correspond to the DelayBasedTimeSource that uses
-// the base::TimeTicks::Now as the timebase.
-scoped_refptr<DelayBasedTimeSource> DelayBasedTimeSource::Create(
-    base::TimeDelta interval,
-    base::SingleThreadTaskRunner* task_runner) {
-  return make_scoped_refptr(new DelayBasedTimeSource(interval, task_runner));
-}
-
-DelayBasedTimeSource::DelayBasedTimeSource(
-    base::TimeDelta interval,
-    base::SingleThreadTaskRunner* task_runner)
-    : client_(NULL),
-      last_tick_time_(base::TimeTicks() - interval),
-      current_parameters_(interval, base::TimeTicks()),
-      next_parameters_(interval, base::TimeTicks()),
-      active_(false),
-      task_runner_(task_runner),
-      weak_factory_(this) {
-  DCHECK_GT(interval.ToInternalValue(), 0);
-}
-
-DelayBasedTimeSource::~DelayBasedTimeSource() {}
-
-base::TimeTicks DelayBasedTimeSource::SetActive(bool active) {
-  TRACE_EVENT1("cc", "DelayBasedTimeSource::SetActive", "active", active);
-  if (active == active_)
-    return base::TimeTicks();
-  active_ = active;
-
-  if (!active_) {
-    weak_factory_.InvalidateWeakPtrs();
-    return base::TimeTicks();
-  }
-
-  PostNextTickTask(Now());
-
-  // Determine if there was a tick that was missed while not active.
-  base::TimeTicks last_tick_time_if_always_active =
-    current_parameters_.tick_target - current_parameters_.interval;
-  base::TimeTicks new_tick_time_threshold =
-    last_tick_time_ + current_parameters_.interval / kDoubleTickDivisor;
-  if (last_tick_time_if_always_active >  new_tick_time_threshold) {
-    last_tick_time_ = last_tick_time_if_always_active;
-    return last_tick_time_;
-  }
-
-  return base::TimeTicks();
-}
-
-bool DelayBasedTimeSource::Active() const { return active_; }
-
-base::TimeTicks DelayBasedTimeSource::LastTickTime() const {
-  return last_tick_time_;
-}
-
-base::TimeTicks DelayBasedTimeSource::NextTickTime() const {
-  return Active() ? current_parameters_.tick_target : base::TimeTicks();
-}
-
-void DelayBasedTimeSource::OnTimerFired() {
-  DCHECK(active_);
-
-  last_tick_time_ = current_parameters_.tick_target;
-
-  PostNextTickTask(Now());
-
-  // Fire the tick.
-  if (client_)
-    client_->OnTimerTick();
-}
-
-void DelayBasedTimeSource::SetClient(TimeSourceClient* client) {
-  client_ = client;
-}
-
-void DelayBasedTimeSource::SetTimebaseAndInterval(base::TimeTicks timebase,
-                                                  base::TimeDelta interval) {
-  DCHECK_GT(interval.ToInternalValue(), 0);
-  next_parameters_.interval = interval;
-  next_parameters_.tick_target = timebase;
-
-  if (!active_) {
-    // If we aren't active, there's no need to reset the timer.
-    return;
-  }
-
-  // If the change in interval is larger than the change threshold,
-  // request an immediate reset.
-  double interval_delta =
-      std::abs((interval - current_parameters_.interval).InSecondsF());
-  double interval_change = interval_delta / interval.InSecondsF();
-  if (interval_change > kIntervalChangeThreshold) {
-    TRACE_EVENT_INSTANT0("cc", "DelayBasedTimeSource::IntervalChanged",
-                         TRACE_EVENT_SCOPE_THREAD);
-    SetActive(false);
-    SetActive(true);
-    return;
-  }
-
-  // If the change in phase is greater than the change threshold in either
-  // direction, request an immediate reset. This logic might result in a false
-  // negative if there is a simultaneous small change in the interval and the
-  // fmod just happens to return something near zero. Assuming the timebase
-  // is very recent though, which it should be, we'll still be ok because the
-  // old clock and new clock just happen to line up.
-  double target_delta =
-      std::abs((timebase - current_parameters_.tick_target).InSecondsF());
-  double phase_change =
-      fmod(target_delta, interval.InSecondsF()) / interval.InSecondsF();
-  if (phase_change > kPhaseChangeThreshold &&
-      phase_change < (1.0 - kPhaseChangeThreshold)) {
-    TRACE_EVENT_INSTANT0("cc", "DelayBasedTimeSource::PhaseChanged",
-                         TRACE_EVENT_SCOPE_THREAD);
-    SetActive(false);
-    SetActive(true);
-    return;
-  }
-}
-
-base::TimeTicks DelayBasedTimeSource::Now() const {
-  return base::TimeTicks::Now();
-}
-
-// This code tries to achieve an average tick rate as close to interval_ as
-// possible.  To do this, it has to deal with a few basic issues:
-//   1. PostDelayedTask can delay only at a millisecond granularity. So, 16.666
-//   has to posted as 16 or 17.
-//   2. A delayed task may come back a bit late (a few ms), or really late
-//   (frames later)
-//
-// The basic idea with this scheduler here is to keep track of where we *want*
-// to run in tick_target_. We update this with the exact interval.
-//
-// Then, when we post our task, we take the floor of (tick_target_ and Now()).
-// If we started at now=0, and 60FPs (all times in milliseconds):
-//      now=0    target=16.667   PostDelayedTask(16)
-//
-// When our callback runs, we figure out how far off we were from that goal.
-// Because of the flooring operation, and assuming our timer runs exactly when
-// it should, this yields:
-//      now=16   target=16.667
-//
-// Since we can't post a 0.667 ms task to get to now=16, we just treat this as a
-// tick. Then, we update target to be 33.333. We now post another task based on
-// the difference between our target and now:
-//      now=16   tick_target=16.667  new_target=33.333   -->
-//          PostDelayedTask(floor(33.333 - 16)) --> PostDelayedTask(17)
-//
-// Over time, with no late tasks, this leads to us posting tasks like this:
-//      now=0    tick_target=0       new_target=16.667   -->
-//          tick(), PostDelayedTask(16)
-//      now=16   tick_target=16.667  new_target=33.333   -->
-//          tick(), PostDelayedTask(17)
-//      now=33   tick_target=33.333  new_target=50.000   -->
-//          tick(), PostDelayedTask(17)
-//      now=50   tick_target=50.000  new_target=66.667   -->
-//          tick(), PostDelayedTask(16)
-//
-// We treat delays in tasks differently depending on the amount of delay we
-// encounter. Suppose we posted a task with a target=16.667:
-//   Case 1: late but not unrecoverably-so
-//      now=18 tick_target=16.667
-//
-//   Case 2: so late we obviously missed the tick
-//      now=25.0 tick_target=16.667
-//
-// We treat the first case as a tick anyway, and assume the delay was unusual.
-// Thus, we compute the new_target based on the old timebase:
-//      now=18   tick_target=16.667  new_target=33.333   -->
-//          tick(), PostDelayedTask(floor(33.333-18)) --> PostDelayedTask(15)
-// This brings us back to 18+15 = 33, which was where we would have been if the
-// task hadn't been late.
-//
-// For the really late delay, we we move to the next logical tick. The timebase
-// is not reset.
-//      now=37   tick_target=16.667  new_target=50.000  -->
-//          tick(), PostDelayedTask(floor(50.000-37)) --> PostDelayedTask(13)
-base::TimeTicks DelayBasedTimeSource::NextTickTarget(base::TimeTicks now) {
-  base::TimeTicks new_tick_target = now.SnappedToNextTick(
-      next_parameters_.tick_target, next_parameters_.interval);
-  DCHECK(now <= new_tick_target)
-      << "now = " << now.ToInternalValue()
-      << "; new_tick_target = " << new_tick_target.ToInternalValue()
-      << "; new_interval = " << next_parameters_.interval.InMicroseconds()
-      << "; tick_target = " << next_parameters_.tick_target.ToInternalValue();
-
-  // Avoid double ticks when:
-  // 1) Turning off the timer and turning it right back on.
-  // 2) Jittery data is passed to SetTimebaseAndInterval().
-  if (new_tick_target - last_tick_time_ <=
-      next_parameters_.interval / kDoubleTickDivisor)
-    new_tick_target += next_parameters_.interval;
-
-  return new_tick_target;
-}
-
-void DelayBasedTimeSource::PostNextTickTask(base::TimeTicks now) {
-  base::TimeTicks new_tick_target = NextTickTarget(now);
-
-  // Post another task *before* the tick and update state
-  base::TimeDelta delay;
-  if (now <= new_tick_target)
-    delay = new_tick_target - now;
-  task_runner_->PostDelayedTask(FROM_HERE,
-                                base::Bind(&DelayBasedTimeSource::OnTimerFired,
-                                           weak_factory_.GetWeakPtr()),
-                                delay);
-
-  next_parameters_.tick_target = new_tick_target;
-  current_parameters_ = next_parameters_;
-}
-
-std::string DelayBasedTimeSource::TypeString() const {
-  return "DelayBasedTimeSource";
-}
-
-std::string DelayBasedTimeSourceHighRes::TypeString() const {
-  return "DelayBasedTimeSourceHighRes";
-}
-
-void DelayBasedTimeSource::AsValueInto(
-    base::trace_event::TracedValue* state) const {
-  state->SetString("type", TypeString());
-  state->SetDouble("last_tick_time_us", LastTickTime().ToInternalValue());
-  state->SetDouble("next_tick_time_us", NextTickTime().ToInternalValue());
-
-  state->BeginDictionary("current_parameters");
-  state->SetDouble("interval_us",
-                   current_parameters_.interval.InMicroseconds());
-  state->SetDouble("tick_target_us",
-                   current_parameters_.tick_target.ToInternalValue());
-  state->EndDictionary();
-
-  state->BeginDictionary("next_parameters");
-  state->SetDouble("interval_us", next_parameters_.interval.InMicroseconds());
-  state->SetDouble("tick_target_us",
-                   next_parameters_.tick_target.ToInternalValue());
-  state->EndDictionary();
-
-  state->SetBoolean("active", active_);
-}
-
-}  // namespace cc